1. Technical Field
The present invention relates to an autoinjector with a novel needle depth adapter useful for applications including administering injections to both humans and animals. More particularly, the present invention relates to autoinjectors capable of injecting medicaments into a precise location within the subject. Furthermore, this invention can be specially adapted for subcutaneous injections and also includes a novel method of administering medicaments to a desired depth within a patient.
2. Background Art
Autoinjectors have become quite popular and have experienced widespread use due to a variety of advantages autoinjectors have over typical manual syringe injectors. Essentially, an autoinjector is an automatic injection system which is designed to deliver a specific dosage of a liquid medicament into an individual. Through their pen-styled design, autoinjectors are fairly simple to use and often have design characteristics enabling an individual to administer a self-injection. The majority of autoinjectors in production today are spring-loaded autoinjectors which provide an individual with less hesitation in self-administering liquid medicaments than would a manual syringe and needle. Furthermore, automatic injectors are much simpler to use in times of stress, pain, or other medical ailments and require less concentration than would a standard manual syringe and needle.
An additional advantage of autoinjectors is that these injectors contain a specific size dose of a liquid medicament sealed within and can be stored for a significant duration. Despite the capability for being stored for a significant duration, the autoinjector is still able to provide an immediate injection even under severe medical stress. Furthermore, automatic injectors will deliver a previously determined dosage of the medicament upon activation, thus precluding the need to measure the specific amount of medicament needed at the time the injection is administered.
Depending on the type of drug and the ailment which the medicament is designed to alleviate, the autoinjector is designed to penetrate to a certain depth. Commonly, most autoinjectors are used for intramuscular injections and have only most recently been designed to provide for subcutaneous injections. Specifically, certain medicines, especially medicines for alleviating migraine headaches, must be injected in the subcutaneous region of a patient rather than have the injection site be at an intramuscular location. The key design consideration in creating an autoinjector for a subcutaneous injection is to attempt to insure that the needle of the autoinjector does not penetrate to a depth beyond the subcutaneous region of the patient. For example, in Sarnoff et al., U.S. Pat. No. 5,102,393, an autoinjector is disclosed which claims to be convertible from an intramuscular to subcutaneous mode of injection. The autoinjector of the '393 patent is taught to have the capability of being actuated in a manner so as to cause virtually no compression of the subcutaneous tissue under the skin at the injection site of the user. For using the autoinjector of the '393 patent in a subcutaneous mode, another device is secured to the autoinjector which attempts to preclude the needle from extending substantially beyond the subcutaneous tissue.
In U.S. Pat. No. 5,873,856, Hjertman et al., a device is disclosed which claims to have a limited depth penetration needle housing. The '856 patent teaches a device which can be adjusted for specific depths of penetration which claims to include a subcutaneous depth of penetration. Furthermore, the disclosure teaches a device where one can readily adjust the needle penetration depth between different pre-set values.
In Saied et al., U.S. Pat. No. 6,312,412, injectors are disclosed which can provide for either intramuscular or subcutaneous injection. The specific injector of the '412 patent includes means for adjusting the medication needle so that the medication needle can be inserted to varying depths within the patient.
De La Serna et al. (U.S. Pat. No. 7,011,649) describes a syringe cartridge which may include an adjustable tip which will allow a user to easily adjust the injection depth for the desired application.
Unfortunately, autoinjectors produced by the prior art processes are not effective for administering subcutaneous injections at an exact and repeatable depth of penetration. The injectors generally available do not have as tight a range of penetration depth as is desired, and furthermore, include needle tips which are adjustable and provide for another variable which can lead to an incorrect penetration depth in times of emergency trauma. In addition, prior art subcutaneous injectors do not include a method wherein the depth of penetration is limited to a small range of penetration depths.
What is desired, therefore, is an autoinjector which has a tight range regarding the needle's depth of penetration wherein the medicament contained within the autoinjector is injected into a specific location within the patient, including the subcutaneous region. Indeed a combination of characteristics including a much more precise range of penetration depths as well as simplicity of use have been found to be necessary for the use of autoinjectors for administering specific medicament into the subcutaneous region of a subject. Also desired is the method for providing more exact injections, including injections within the subcutaneous region.